Maybe USB in the PC world can't handle being moved from
port to port, but on my MacbookPro the machine doesn't care
which of the two USB ports I plug a peripheral (printer, USB
drive, etc.) into - it always finds it, and then uses it immediately.

Ditto for Windows. Let's not turn this into Windows bashing.

Just to make it clear... You can plug any USB device into any port at any
time, and the correct driver will be found and loaded. If you plug it into a
port where it has previously been installed, the driver might be found a bit
faster.

Furthermore, USB can handle up to 256 devices.

I can only defend USB "negatively" -- I've never had problems with it.